Another vote for 3/4 ton, esp. if you are in Ca. and expect to be towing up & down a lot of mountains and hills and on lots of curvy roads. I love the V10 and 4.10 gears in our F250. It never lacks for power, accelerates great, handles great and brakes great. Gets average mpg when towing but not that good for short local trips (not an issue for mostly towing use). If you can find the right truck, I'd avoid 4WD.
We bought our '09 F250 as a fleet return for a pretty good price. We upgraded from an F150 and would never go back to a 1/2 ton except for a shorter & lighter TT (now tow a 29' 7K lb TT).